What to do now?
We have a strip of grass lawn between the sidewalk and curb that has been ravaged by some kind of grubs. In these areas the grass has died and its roots have been eaten away. Am I better off replacing the entire area with sod or planting grass seed? About half to three-quarters of the area is now just dirt. And should I be treating this area for grubs and, if so, with what?
The strip of grass that has died from insect feeding should either be reseeded very soon (getting late in year) or planted with sod. The best time for seeding is early September because this gives time for the grass to germinate and much of the fall to develop a root system, however the area could still be seeded but should be handled before mid-October. It is important to make sure you get good soil/seed contact when you seed, so old vegetation must be removed or tilled into the new seed bed. After seeding, the area needs to remain moist for successful germination and early plant establishment. Seeding grass in the spring is possible however not the best time to do so because there is so little time for the grass plant to germinate, grow, establish and develop a root system sufficient for surviving hot summers.
It is also getting late in the year for treating white grubs as they are about to move deeper into the soil profile for winter. If you are certain it is a grub issue, then treatments with a number of products at garden centers/big box stores are available. Applications should be made within the next week. If this timing is missed, some of these products also work with an earlier timing such as between mid-June and mid-July depending on the product used. The label on the product will provide instructions as to its use. Products vary but may include pyrethroids (active ingredient ends in -thrin), imidacloprid (active ingredient), chlorantraniliprole (active ingredient), or carbaryl (active ingredient). Early spring treatment for grubs is often not cost effective as the grass tolerates feeding since the grass is actively growing.